The fossil skeletons of radiolarians are very three dimensional, making them a tough subject to photograph with a microscope. Stacking with Helicon Focus allows for some nice looks at these structures.

I can see there is kind of aberration on the images? I think they can be improved by shifting blue channel up and red channel down. What is the reason for this aberration?

Not really. These were done with DIC (Differential Interference Contrast) illumination. When used "normally" with a subject like this the results are shades of a uniform color (there is no real color in these silica "skeletons" at all). By changing the relative positions of the upper an lower Nomarski prisms you can get some very weird and colorful ("DisneyChrome", I call it ) renditions. I use DIC this way infrequently, but sometimes it is fun to try with otherwise colorless subjects. A more proper name for this is "Optical Staining" and it can be studied in more detail here:http://www.olympusmicro.com/primer/java ... index.html

Here's another stacked radiolarian image so you can see what the DIC effect would be without adjusting it into this "optical staining" range.